I would not recommend it unless your will to brick your WRP200. The firmware that Vonage uses is proprietary special builds that Vendors like Linksys develop based upon Vonage requirements. They usually are not universal.

There is even a chance the WRP200 would be smart enough to know this is not correct firmware and not allow it to install. However there is also a chance it will allow it to install and could possibly seem to work however certain features or functions may not work correctly.

I know you don't use it with Vonage since that is not a Vonage piece of hardware and only devices that are packaged for Vonage can be used with Vonage. They do not allow you to bring your own device. But that has nothing to do with my answer. I was just telling you that just because they look the same does not mean you can apply any firmware to it. Vonage firmware is a special build for their devices only.

To be completely honest your better off getting a good wireless router and using a separate SIP based Voip telephone adapter. The reason I say this is when a manufacturer tries to combine too many things into a single piece of hardware, one or both of technologies combined are usually never 100%.